Protective coating for decorated glassware and method of application



July 21, 1959 E. F. SCHAEFER 2,895,846 PROTECTIVE COATING FOR DECORATED GLASSWARE AND METHOD OF APPLICATION Filed May 25, 1955 A'ITORNEYS United States. Patent "ice PROTECTIVE COATING FOR nECoRATEbonAss- I WARE AND METHOD OF APPLICATION Earl'E-Schaefer, Toledo; Ohio, assignor to'r0wens-lllinois The present invention!relatess toidecoratedi glassware "and more specifically to a protective coating'for the preservation of decorative and printed designs on glass-bottles,

jars-or other such wareand arsimple, convenient method t fof. application of the coating.

.The designs are usuallyz-co'mposediofi printingleinks which maybe applied'by anyaone of-numerousmethods of: application suchas printing,: stenciling ore-silk screening. The fixation of the-designs isusually accomplished by the application of heat to permanentlyfuse the print- .-ing .ink .onto 'the:g1ass,"the temperature 'level" required ..are weakened by such exposure and rendered ..more

susceptible" to removalb'y scratching or abrasivecofitact with other surfaces. Thus, incompoufiding printing'l'inks for decorative purposes'it 'is essential that theirfr'e'sistance to water and abrasion be evaluated rior to their adoption and use.

'Accor'dinglyjit'is' aprincipal "object. of thi invention to provide aprotective coating for"decorative'd'e"signs on glassware which coating is'lfirmly bonded to the external surfaces of said designs to markedlyrimproventheir re-' sistance. to water and. abrasion=as-well asitoa-minimize the limiting tendencies of these properties: in the adoption anduse of manyof-the ink compositions.

Another object =-of 2 this invention is toprovide a protective coating fordecorativeides ig-nson, glasswarewhich is adaptable to application as part of the normal decorating fixing step after hot or cold color applications of the decorating materials.

The specific nature of this invention, as well as other objects and advantages thereof, will become apparent to those skilled in the art from the following detailed description taken in conjunction with the annexed sheet of drawings, on which by way of preferred example only, is illustrated one embodiment of this invention.

Referring to the accompanying drawings:

Fig. 1 is a fragmentary side elevational view of the discharge end of a conventional decorating lehr showng the interior in broken lines:

Fig. 2 is a fragmentary sectional plan view of a bottle Wall; and

Fig. 3 is a side elevational view of a decorated bottle.

In the illustration of an embodiment of my invention the discharge end portion of a conventional decorating lehr is shown in Fig. l with a continuous traveling conveyor 11 formed of reticulated material upon which the decorated products are finished. The decorated products consist of glass bottles 12 or other similar glass articles which are carried upon the continuously moving conveyor 11 through the desired temperature zones of the lehr 10 at a controlled rate of speed in the decoration fixing operation. In Fig. 1 the glass bottles 12 are shown 2,895,846 :Patented July" 21, 1959 2 ii'spaed'apart within the lehr 10 in upright positions. upon 'i. the.:conveyor 11;

' Theexternal surfaces of the bottles? 12' are'decorated l withvprinting ink'designs 16, one: bottle being'shoWn-in 5 i-l-lig; 3. :with the decoratedletter X, prior to the application iiofi thevprotective coating. Thedecoratingb'ottles 12 are carried'through the lehr '10 for the required length of time tia theaproperltemperaturelevelsto. properly fuse or bake i 'i'the'designs' 16 ontoihe' glass. The designs 16 may be ap- IOa'pIied hot'rorl cold prior to the fusing or baking operation depending upon the type of printing ink composition =ernployed and' the method of application selected. As is iclistornaryrin: the: expedient manufacture of decorated ::glass bottles. the designs 16 after their :proper application 'inunfixed' form are permanentlyfusd'to the glasswithin 5 the decorating lehr 10 or a similar. baking oven usually by :heating: thebottles 12 to a temperature in excess of :;450 F.

' 'iThe' majority of printing inks used fori decorative pur- 20; poses: on glassware; contain silicone resins to obtain the tn'nost desirableproperties of clearly defined andfirmly bonded decorative patterns. 'In the present :invention theius'e'of'p'rinting inks containing-silicone resins is ":Ipreferable althoug'h satisfactory results have been ob- :-;tained" with: ordinaryprinting inks whichzdo not contain silicone" resins.

nIn my; invention :the'decorated iglass 'bottles12 are coated with a protective film 17'of 's'iliconesmaterial while 1 npassingzthroug'h' thezlower' I temperature 'zone of .the' lehr z' tunnels-at its dis'charge'end. The silicone material-conwSlStS of a-synthetic' silicone resin which forms a thin film -f17 overfthe decorated surfaces of the baked; printing =ink -.desiigns--16 land the surroundingglass surfaces of the .a-bottles 12. The silicoue'materialcomprising the'protective film s17.- maybe applied'over theprinting ink designs 16 by -:vaporizing'a solution containing a'silicone compound onto .the bottles 12 by the use of heat. The commerciallyavailable silicone solutions are generally composed 40, of.,silicone resins ofmixed siloxane copolymers having volatile aromatic' hydrocarbons as theinsolvents. T-he .ruse of such organic solutions is objectionable in com- ..mercial practice in that solventrecovery systems are .-.needed.and some hazard exists in connection with the volatile solvents being .flammable.

L I,.' have. found that. a practical :and easy method .of application is to apply the silicone 'film 17 in the form of a water emulsion by spraying or fogging the aqueous solution into the lehr 10 during the latter stages of the 5 decorating operation. Thus, the permanent fixation of both the decorating material and the protective coating can be accomplished in one operation. The organic silicone material is diluted with water to form an aqueous emulsion containing only a small amount of the silicone.

Any of the commercial silicone emulsions which on polymerization give high water repellency to glass and which can be dispersed in water may be used. Examples suitable in this regard are the product of General Electric Corporation identified as SM-70, and a product of Dow-Corning Corporation identified as EF4010.

The concentration of the silicone in the aqueous emulsion is adjusted to from 0.5 to 2.0 percent, the amount, however, not being critical for satisfactory deposition of the film. The film 17 is quite thin, being much thinner than the decorative design 16. With the silicone comprising an emulsion in water no special precautions against combustion or solvent recovery systems are required.

Spray equipment of any conventional type may be used within the lower temperature range of the lehr 10 relatively near the discharge end. The preferable type of spray pattern is produced within the lehr 10 by a manifold 13 extending transversely across the upper portion of the lehr with suitable spray nozzles 14 directed.

downward toward the upright bottles 12. The spray pattern is directed downward directly over the tops of the bottles 12 to insure complete coverage; The manifold 13 is constructed to be adjustable for height over the bottles 12 to allow various size bottles to be-spray coated. The adjustability of the manifold 13 also permits control over the amount of silicone deposited. The spray manifold 13 is located within the lehr 10 in a position where the usual operating temperature of the ware is within the range of from 300 to 450 F. The size and shape of the spray nozzles 14 are not critical, but a type which produces a mist-like spray having fine particle size is most desirable. i

It has been found that the downwardly directed spray 15 does not have to directly contact the surfaces of the bottles 12 but because of the rapid vaporization of the water of the emulsion the bottles 12 are treated either from the vaporized silicone or the silicone carried in the air currents within the lehr 10. Air currents carry the silicones along to contact the bottles 12 after the water of the emulsion has been vaporized by the heat of the lehr. Thus, good coverage of the external surfaces of the bottles over their decorated and undecorated external surfaces is obtained without direct impingement of a liquidus phase of the emulsion. The silicone film 17 is comprised of a low molecular, invisible layer over the decorated design 16 and the glass bottle 12 which causes both to become water repellent. Sufiicient material is sprayed over the bottle to give a thin silicone coating high in water repellency.

Normal operation of the decorating lehr 10 allows sufficient time to cure the silicone coating as well as the' printing ink designs. By applying the silicone as an adjunct to the decorating operation its application may be accomplished at very nominal cost. Water resistance of the printed designs is increased many fold and the designs are made considerably more durable.

The silicone coating or him 17 is most eifective when used with a printing ink incorporating a silicone resin in its composition because of the chemical bond which is established between the silicones of theink and the coating. The temperature range of 300 to, 450 F. in which the spray 15 is applied furnishes a very suitable condition for the establishment of silicone bonding reactions. The silicone coating applied at the time of baking of the ink thus chemically bonds directly to the silicone of the ink itself when such decorating inks are employed, creating a more water-proof and abrasion resistant coating than "is obtained without the finishing treatment of the silicone coating. The coating can also be employed beneficially with inks which do not contain silicone as an ingredient, as such coating becomes firmly bonded to the constituents of ordinary printing inks primarily due to the heat of baking.

Various modifications of this invention may be resorted to within the spirit and scope of the appended claims.

1 glass container to a fine spray of an aqueous emulsion of a silicone resin constitutingfrom 0.5% to 2.0% by weight of the total weight of emulsion until the entire external. surfaceof the decorated glass container is provided with -a uniform coating while within said range of 1 temperature, (5) maintaining said silicone coated decorated glass container within said temperature range until said coating is cured, and (6) cooling said decorated coated container to room temperature.

- 1 2; A glass article which is the product of the method defined in claim 1.

-McGraw-Hill Book Company, Inc. (New York), 1954.

' References Cited in the file of this patent UNITED STATES PATENTS Kneip Dec. 3, 1935 2,428,357 Cohen Oct. 7, 1947 2,436,304 Johannson Feb. 17, 1948 2,495,306. "Zurcher Jan. 24, 1950 2,582,919 Biefeld Jan. 15, 1952 2,588,828. Greiner. Mar. 11, 1952 Bennett et al. Dec. 6, 1955 OTHER REFERENCES Silicones and Their Uses (McGregor), published by (Page 213 relied on.)

Printed Circuit Techniques," National Bureau of Standards Circular #468, United States Department of Commerce, National Bureau of Standards. 

1. THE METHOD OF PRODUCING A DECORATED GLASS CONTAINER WHICH BEARS AN ADDITIONAL PROTECTIVE COATING CAPABLE OF IMPROVING THE WATER AND ABRASION RESISTANCE OF THE DECORATION, SAID METHOD COMPRISING THE CONTINUOUS, UNINTERRUPTED SEQUENCE OF STEPS OF (1) APPLYING A TEMPERATURE-HARDENABLE PRINTING INK DECORATION TO SELECTED AREAS OF THE GLASS CONTAINER, (2) HEATING SAID GLASS CONTAINTER TO A TEMPERATURE ABOVE 450* F. TO BOND THE PRINTING INK DECORATION THERETO, (3) LOWERING THE TEMPERATURE OF THE DECORATED GLASS CONTAINER TO A TEMPERATURE TO BETWEEN 300* F. AND 400* F., (4) SUBJECTING SAID DECORATED GLASS CONTAINER TO A FINE SPRAY OF AN AQUEOUS EMULSION OF A SILICONE RESIN CONSITUTING FROM 0.5% TO 2.0% BY WEIGHT OF THE TOTAL WEIGHT OF EMULSION UNTIL THE ENTIRE EXTERNAL SURFACE OF THE DECORATED GLASS CONTAINER IS PROVIDED WITH A UNIFORM COATING WHILE WITHIN SAID RANGE OF TEMPERATURE, (5) MAINTAINING SAID SILICONE COATED DECORATED GLASS CONTAINER WITHIN SAID TEMPERATURE RANGE UNTIL SAID COATING IS CURED, AND (6) COOLING SAID DECORATED COATED CONTAINER TO ROOM TEMPERATURE. 